<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
body{
margin:0;
padding:0;
}
ul,li{
margin:0;
padding:0;
}
ul,li{
list-style: none;
}
ul li{
width: 200px;
height: 100px;
background:yellow;
margin-bottom: 20px;
filter:alpha(opacity:30);
opacity: 0.3;
border:4px solid #000;
}
</style>
<script type="text/javascript">
window.onload=function(){
var li1 = document.getElementById('li1');
var li2 = document.getElementById('li2');
li1.onmouseover = function(){
startMove(this,'opacity',100);
}
li1.onmouseout = function(){
startMove(this,'opacity',30);
}
}
function getStyle(obj,attr){
if(obj.currentStyle){
return obj.currentStyle[attr];
}else{
return getComputedStyle(obj,false)[attr];
}
}
function startMove(obj,attr,target){
clearInterval(obj.timer);
obj.timer=setInterval(function(){
var icur=0;
if(attr == 'opacity'){//假设attr是opacity
var icur = parseFloat(getStyle(obj, attr))*100;//parseInt取整，不能得到opacity
}else{
var icur = parseInt(getStyle(obj, attr));
}
var speed = (target-icur)/8;
speed=speed>0?Math.ceil(speed):Math.floor(speed);
if(icur == target){
clearInterval(obj.timer);
}else{
if(attr == 'opacity'){//假设attr是opacity
obj.style.filter = 'alpha(opacity:'+(icur+speed)+')';
obj.style.opacity=(icur+speed)/100;
}else{
obj.style[attr]=icur + speed+'px';
}
}
},30);
}
</script>
</head>
<body>
<ul>
<li id="li1"></li>
</ul>
</body>
</html>目的是封装一个运动框架，现已兼容width和opacity属性